Volkswagen Golf Transmission Fault
If your automatic gearbox suddenly refused to change gear properly, would you know what to do?
Mr P knew something wasn’t right. His 2020 Volkswagen Golf had started shifting erratically, struggling to select certain gears during normal driving. On top of that, a transmission fault warning had appeared on the dashboard, making the situation impossible to overlook.
The problem had developed without any lead-up. One day the gearbox was working normally, the next it wasn’t. Mr P had no way of knowing whether the car was safe to continue driving, whether the issue would deteriorate further, or what the underlying cause might be.
Mr P got in touch with Fitch Autos, Brownhills, hoping to get to the bottom of the problem. The symptoms were characteristic of a Volkswagen Golf transmission fault that required accurate identification and a professional repair.
What he needed was a team with genuine diagnostic expertise and a methodical approach to locate the fault and put it right.
With that, Mr P booked the Golf in with Fitch Autos for a full technical evaluation.
Understanding the Driver’s Concerns and Early Findings
The first thing our technicians did when the Volkswagen Golf arrived at Fitch Autos, Brownhills, was sit down with Mr P to hear the full detail of what he had noticed. We wanted to establish when the unpredictable gear changes had first appeared, how consistently the problem was presenting, and whether anything changed with driving conditions such as speed, ambient temperature, or journey duration.
Getting a full account of the symptoms before any physical testing takes place gives our technicians a much clearer starting point, and helps make sure nothing that could be relevant is missed.
Following this, our technicians took the Golf out on a road test to observe the fault directly. Manufacturer-level diagnostic equipment was connected to the vehicle throughout the drive, capturing serial data from the transmission control module in real time. This gave our technicians a live window into how the system was behaving the moment the fault presented itself.
At the same time, a full system scan was completed. It returned a stored fault code with a clear link to the Volkswagen Golf transmission fault:
- P1736 00 — Position sensor for clutch 2, electrical malfunction. Active.
This told our technicians that the transmission control module had logged an electrical fault involving one of the internal sensors used to monitor clutch operation. But reaching the right conclusion through a transmission warning light diagnosis takes more than reading a code. It requires understanding what that code actually points to.
To get to the bottom of what the Volkswagen P1736 fault code had recorded, and to be certain the correct next steps were taken, a deeper investigation was required.
The Underlying Cause Behind the Reported Symptoms
Fault code P1736 had been identified, pointing to an electrical malfunction with the position sensor for clutch 2. However, our technicians needed to go further. Before the right repair could be carried out for this Volkswagen Golf transmission fault, it was essential to establish precisely what had failed and why. Every relevant area was examined in a structured sequence to reach a reliable, evidence-backed conclusion.
Step 1: Consulting manufacturer technical data
Our technicians accessed Volkswagen’s technical information service to study the theory of operation for the transmission in Mr P’s Golf.
The 2020 Golf was fitted with a seven-speed Direct Shift Gearbox (DSG), a dual-clutch transmission that features widely across the Golf range. The system relies on two separate clutches: clutch 1 is responsible for odd gears (1, 3, 5, 7) and clutch 2 is responsible for even gears (2, 4, 6, and reverse). Gear selection and clutch engagement are both controlled by a mechatronic unit, which brings together the transmission control unit (TCU) and a hydraulic valve body.
A critical detail is that clutch position in this transmission is not monitored by a standalone external sensor. Instead, the mechatronic unit contains internal pressure sensors that provide the feedback needed for clutch control, and the system works out clutch position from those pressure readings. When fault code P1736 references “position sensor for clutch 2,” it is pointing to this integrated pressure sensor housed within the mechatronic unit.
This told our technicians something important: the fault was almost certainly internal to the mechatronic unit, rather than originating from a separate externally mounted component.
Step 2: Checking for technical service bulletins
Our technicians searched for any technical service bulletins (TSBs) related to the specific diagnostic trouble code (DTC) and the symptoms Mr P had described.
- A bulletin was found that matched the exact fault code and the reported behaviour
- It confirmed this as a recognised issue affecting DQ381 transmissions, caused by a fault with the integrated pressure sensors inside the mechatronic unit
- The bulletin set out how, as these sensors wear down or drift outside their calibrated range, the TCU begins receiving inaccurate pressure data and miscalculates clutch position, causing erratic shifting and failed gear engagement
This supported what the Volkswagen P1736 fault code had flagged, but our technicians still needed to verify the fault through hands-on testing before committing to a repair.
Step 3: Serial data analysis at rest
With the vehicle stationary, the engine off, and the ignition on, our technicians recorded the actual pressure values for both clutches using manufacturer-level diagnostic equipment.
- In a correctly functioning system, both pressure readings should sit as close to 0.00 bar as possible under these conditions
- The reading for clutch 2 showed a clear deviation from the expected value, consistent with a pressure sensor that had drifted beyond its normal operating range
- The reading for clutch 1 remained within the expected range, confirming that the fault was isolated to the clutch 2 side of the system
This corresponded directly with the Volkswagen P1736 fault code and the symptoms Mr P had described, where the even-numbered gears were the ones being affected.
Step 4: Visual inspection
Our technicians examined the external condition of the mechatronic unit, wiring harness, and connectors for any signs of damage, corrosion, or compromised connections.
- No external issues were found, eliminating any cause outside the mechatronic unit itself
The conclusion
With the Volkswagen P1736 fault code now fully accounted for, the integrated pressure sensor for clutch 2, located on the TCU circuit board inside the mechatronic unit, had drifted outside its operating specification. It was no longer capable of accurately measuring hydraulic pressure for the clutch 2 sub-transmission, which caused the system to miscalculate clutch position and led to incorrect engagement of the even-numbered gears.
Because this sensor forms part of the internal mechatronic assembly, it is not available as a separate serviceable component. The mechatronic unit needed to be replaced.
Resolving the Issue with the Correct Repair
With the root cause pinpointed through structured testing, our technicians spoke with Mr P to explain everything that had been found and outline the repair that was needed. After receiving his approval, the work got underway.
Mechatronic unit replacement
- The transmission oil was drained and access to the mechatronic unit was gained by removing the transmission oil pan and associated components
- The faulty mechatronic unit was carefully disconnected and removed from the vehicle
- A replacement mechatronic unit was installed, with all electrical connections, mounting points, and seals inspected to confirm correct fitment
- Fresh transmission oil was added to the correct Volkswagen specification, in line with manufacturer procedure
Calibration and adaptation
- Manufacturer-level diagnostic software was used to complete a calibration and adaptation procedure, which is a necessary step following any mechatronic replacement. This enables the new TCU to adjust to the existing tolerances of the transmission and clutch mechanics
- All stored fault codes were cleared from the system
Post-repair road test
- A structured road test was carried out, giving the transmission the opportunity to complete its clutch adaptation under real driving conditions
- The vehicle was monitored throughout to confirm that gear changes were smooth, no gears were being missed, and no new fault codes had appeared
The Result for Mr P and His Volkswagen Golf
The Volkswagen gearbox mechatronic repair resolved the Volkswagen Golf transmission fault completely, restoring the transmission to smooth, consistent operation with no warning messages on the dashboard.
The root cause was identified and repaired during a single visit, thanks to a structured, evidence-led technical evaluation carried out by our technicians at Fitch Autos. The automatic transmission fault repair was completed to manufacturer standards, using the same technical data and equipment available at a main dealership. Mr P received all of this at a more competitive price than a main dealer, and a complimentary courtesy car was provided throughout the repair to keep disruption to a minimum.
Mr P collected his Golf from Fitch Autos reassured, with smooth gear changes restored and no warning lights in sight.
Volkswagen Transmission Issues? Call Fitch Autos Before It Gets Worse
If your Volkswagen is shifting erratically, missing gears, or displaying a transmission warning on the dashboard, getting it checked sooner rather than later is essential. Continuing to drive with a transmission fault can place increasing strain on internal components and lead to more costly repairs down the line.
By choosing Fitch Autos in Brownhills, you benefit from:
- Technicians experienced in diagnosing complex Volkswagen transmission faults
- Access to manufacturer-level technical data, service bulletins, and dealer-level equipment
- A structured, evidence-led technical evaluation process
- More cost-effective repairs than a main dealer
- A complimentary courtesy car to keep you mobile while the work is carried out
- A 12-month parts and labour guarantee for added peace of mind
Our {{average-rating}} star rating from {{review-count}} Google reviews speaks for itself. If your Volkswagen needs expert attention, give our team a call on 01543 452630.
